[143.01] Demographics of Double Lobed Radio Quasars

We have constructed a large sample of edge brightened,
double lobed radio sources (FR2 hereafter), selected from
the optical Sloan Digital Sky Survey Data Release 3 (DR3)
preliminary quasar list and the FIRST radio survey. Unlike
positional matching strictly on the quasar position, which
would severely bias against lobe-dominated radio sources
which do not happen to have a detected core component, we
have used the actual radio environment of each quasar.
Plausible radio source configurations are ranked according
to the distance from the quasar position, component flux
densities, and an inferred lobe opening angle. This ranking
process does not care whether a radio core is present at the
optical position, and is rather effective in picking up FR2
sources above the background. About 2% of our quasar sample
of ~50 000 have double lobed radio sources associated
with them.

With this sample, which for the first time is large,
unbiased, and uniform enough, we present new results on the
occurrence of radio activity among quasars, the relative
radio morphological make-up of the radio quasar population,
and the implications the observed core-to-lobe flux density
ratios have on unification models involving viewing angles.
In addition, we present results correlating the (optical)
environment of the quasar with the shape of the radio
source; in particular the lobe-opening angle which tends to
be 180 degrees in the unperturbed, straight case. We find,
however, a significant fraction of our FR2 sample to be
bent, with angles as small as 100 degrees.

Only with the advent of large scale surveys, like the SDSS
and FIRST in this case, can we begin to address the nature
of rare phenomena; rare either due to low levels of
occurrence, or to their relatively short time-scales. The
quasars and their associated radio emission are a prime
example of this.